/*
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (C) 2013 Armink <armink.ztl@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * File: $Id: mbfuncinput_m.c,v 1.60 2013/10/12 14:23:40 Armink Add Master Functions  Exp $
 */

 /* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"

/* ----------------------- Platform includes --------------------------------*/
#include "port.h"

/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mb_m.h"
#include "mbframe.h"
#include "mbproto.h"
#include "mbconfig.h"

/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_REQ_READ_ADDR_OFF            ( MB_PDU_DATA_OFF + 0 )
#define MB_PDU_REQ_READ_REGCNT_OFF          ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_REQ_READ_SIZE                ( 4 )
#define MB_PDU_FUNC_READ_BYTECNT_OFF        ( MB_PDU_DATA_OFF + 0 )
#define MB_PDU_FUNC_READ_VALUES_OFF         ( MB_PDU_DATA_OFF + 1 )
#define MB_PDU_FUNC_READ_SIZE_MIN           ( 1 )

#define MB_PDU_FUNC_READ_RSP_BYTECNT_OFF    ( MB_PDU_DATA_OFF )

/* ----------------------- Static functions ---------------------------------*/
eMBException    prveMBError2Exception(eMBErrorCode eErrorCode);

/* ----------------------- Start implementation -----------------------------*/
#if MB_MASTER_RTU_ENABLED > 0 || MB_MASTER_ASCII_ENABLED > 0
#if MB_FUNC_READ_INPUT_ENABLED > 0

/**
 * This function will request read input register.
 *
 * @param ucSndAddr salve address
 * @param usRegAddr register start address
 * @param usNRegs register total number
 * @param lTimeOut timeout (-1 will waiting forever)
 *
 * @return error code
 */
eMBMasterReqErrCode
eMBMasterReqReadInputRegister(UCHAR ucSndAddr, USHORT usRegAddr, USHORT usNRegs, LONG lTimeOut)
{
    UCHAR* ucMBFrame;
    eMBMasterReqErrCode    eErrStatus = MB_MRE_NO_ERR;

    if (ucSndAddr > MB_MASTER_TOTAL_SLAVE_NUM) eErrStatus = MB_MRE_ILL_ARG;
    else if (xMBMasterRunResTake(lTimeOut) == FALSE) eErrStatus = MB_MRE_MASTER_BUSY;
    else
    {
        vMBMasterGetPDUSndBuf(&ucMBFrame);
        vMBMasterSetDestAddress(ucSndAddr);
        ucMBFrame[MB_PDU_FUNC_OFF] = MB_FUNC_READ_INPUT_REGISTER;
        ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF] = usRegAddr >> 8;
        ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF + 1] = usRegAddr;
        ucMBFrame[MB_PDU_REQ_READ_REGCNT_OFF] = usNRegs >> 8;
        ucMBFrame[MB_PDU_REQ_READ_REGCNT_OFF + 1] = usNRegs;
        vMBMasterSetPDUSndLength(MB_PDU_SIZE_MIN + MB_PDU_REQ_READ_SIZE);
        (void)xMBMasterPortEventPost(EV_MASTER_FRAME_SENT);
        eErrStatus = eMBMasterWaitRequestFinish();
    }
    return eErrStatus;
}

eMBException eMBMasterFuncReadInputRegister(UCHAR* pucFrame, USHORT* usLen)
{  //这个功能码是读取输入寄存器的  //pucFrame指向接收到的modbus数据的第二个字节 即功能码   usLen里面存储的是除 (Address + CRC之外的长度)
    UCHAR* ucMBFrame;
    USHORT          usRegAddress;
    USHORT          usRegCount;

    eMBException    eStatus = MB_EX_NONE;
    eMBErrorCode    eRegStatus;

    /* If this request is broadcast, and it's read mode. This request don't need execute. */
    if (xMBMasterRequestIsBroadcast())
    {
        eStatus = MB_EX_NONE;
    }
    else if (*usLen >= MB_PDU_SIZE_MIN + MB_PDU_FUNC_READ_SIZE_MIN)
    {//上面哪个broadcast是干嘛的
        vMBMasterGetPDUSndBuf(&ucMBFrame);  //这里指向modbus发送帧的功能码 
        usRegAddress = (USHORT)(ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF] << 8);  //要读取寄存器的起始地址的高字节
        usRegAddress |= (USHORT)(ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF + 1]);  //要读取寄存器的起始地址的低字节
        usRegAddress++; //这里加一,后面还得减一

        usRegCount = (USHORT)(ucMBFrame[MB_PDU_REQ_READ_REGCNT_OFF] << 8);  //要读取的寄存器数量的高字节
        usRegCount |= (USHORT)(ucMBFrame[MB_PDU_REQ_READ_REGCNT_OFF + 1]);  //要读取的寄存器数量的低字节

        /* Check if the number of registers to read is valid. If not
         * return Modbus illegal data value exception.
         */
        if ((usRegCount >= 1) && (2 * usRegCount == pucFrame[MB_PDU_FUNC_READ_BYTECNT_OFF]))  //指向数据域字节数
        {   //最低读取一个寄存器  并且  要读取的数据字节数等于实际接受到的字节数
            /* Make callback to fill the buffer. */
            eRegStatus = eMBMasterRegInputCB(&pucFrame[MB_PDU_FUNC_READ_VALUES_OFF], usRegAddress, usRegCount);
            /* If an error occured convert it into a Modbus exception.  pucFrame[MB_PDU_FUNC_READ_VALUES_OFF]指向读取的数据区域*/
            if (eRegStatus != MB_ENOERR)
            {  //表示有错误  
                eStatus = prveMBError2Exception(eRegStatus);
            }
        }
        else
        {
            eStatus = MB_EX_ILLEGAL_DATA_VALUE;
        }
    }
    else
    {
        /* Can't be a valid request because the length is incorrect. */
        eStatus = MB_EX_ILLEGAL_DATA_VALUE;
    }
    return eStatus;
}

#endif
#endif
